The present invention relates to an audio player and, more particularly, to a portable digital audio device which is also structurally and functionally compatible with a cassette player and may therefore also be used as a digital cassette playable by a conventional, i.e., analog, cassette player.
Audio players has tremendously evolved since the introduction of the radio which is an apparatus for receiving or transmitting radio broadcasts telecommunicated employing electromagnetic waves of a particular frequency range to transmit speech or other sound over long distances without the use of wires, and the gramophone, which is the first records player.
Two main recording technologies apply for audio players. The first is analog recording which is a method of sound recording in which an input audio waveform is converted to an analog waveform. The second is digital recording which is a method of recording sound in which an input audio waveform is sampled many thousands of times per second and each sample is given a binary numerical value.
Portable audio players were realized as soon as sufficient miniaturization was technologically feasible.
The first portable audio player was a miniaturized radio device, also known as a radiotransistor or simply as a transistor, which includes a compact solid-state device (radiotransistor) including a semiconductor with three or more electrodes and which performs the primary functions of an electron tube, as amplification, switching, and detection, but uses less power.
Another well known portable audio player is the walkman which is a small portable stereo player used with, or shaped as, headphones, which typically functions both as a radio, and/or as a cassette player. A cassette is a plastic case in which analog audio magnetic tape runs between two reels for use in recording of sound or playing back.
Quickly following the introduction of compact disks (CDs), which include digital audio information, and CD players which are devices designed for playing the audio information stored in CDs, the CD players were miniaturized to become portable. Such portable CD players are known as diskman.
The digital CD technology is superior to analog audio tape in terms of durability and quality, however it is not widely amenable for personal recording of audio information.
The most recent development in portable audio players is the chip based digital player which enjoys both the quality and durability of CDs and which is readily amenable for personal recordings. A digital audio player includes an audio chip and a memory which serve to record, store, and subsequently play digital audio information. Typically, an audio chip is also designed to compress and decompress audio digital data in order to save memory space. Digital audio players became feasible with the co-evolution of miniaturized high capacity digital memory devices and digital information compression technologies.
Thus, MP3, MP4, AT&T, a2b, Liquid Audio, Real Audio and SDMI audio players, which are digital audio players, are becoming widely used. These players enable the download, store and subsequent play compatibly compressed digital audio information from, for example, the Internet.
Many automobiles and homes are equipped with stereo systems. Typically, such stereo systems include a radio, a cassette player and a CD player. Being stationary, such stereo systems are not designed nor are they convenient for download and subsequent play of digital information.
Emulators have therefore been developed to enable a user to play audio digital downloads in such stereo systems.
Such an emulator is shaped as a cassette insertable into a cassette deck of a cassette player. It includes a line connectable to the line-out connector (which typically serves to accept an earphone) of any audio device, including, for example, portable digital players or CD players.
Through the line, the emulator receives audio information input from the audio device and produces audio information output in the form of emulated magnetic information which is recognized by the magnetic playing head of the cassette player and is converted thereby into sound.
This design, however, is limiting. For example, when used with automobile cassette players which have a frontal, uncovered, cassette deck, the portable audio device is not rigidly anchored and may therefore be damaged. Home and other stereo systems typically include a covered cassette deck which is not at all applicable for use with an emulator because the line connecting the emulator to the audio device prevents appropriate closure of the cover. Furthermore, operational commands to the audio device cannot be executed via the control panel of the cassette player.
There is thus a widely recognized need for, and it would be highly advantageous to have, an audio device devoid of the above limitations. Such a device serves both as a portable digital audio device, and yet it is also structurally and functionally compatible with a cassette player and may therefore also be used as a digital cassette playable and controlled by a conventional, i.e., analog, cassette player.